A new study reveals that certain genes related to serotonin or dopamine influence how we make choices based on rewards or punishments we experienced in the past. And this influence largely depends on which gene variant we inherit from our parents.

For the study, Drs. Hanneke den Ouden and Roshan Cools from the Donders Institute and New York University investigated how the brain chemicals dopamine and serotonin help determine our sensitivity to reward and punishment.

“We used a simple computer game to test the genetic influence of the genes DAT1 and SERT, as these genes influence dopamine and serotonin. We discovered that the dopamine gene affects how we learn from the long-term consequences of our choices, while the serotonin gene affects our choices in the short term,” said den Ouden.

“In nearly 700 people we analyzed which variant of the SERT and the DAT1 genes they had,” said den Ouden. “Using an online game, we investigated how well people are able to adjust their choice strategy after receiving a reward or a punishment.”

During the study, participants would repeatedly choose one of two symbols: symbol A, which usually resulted in a reward, or symbol B, which usually resulted in punishment. Halfway through the game, however, these rules were reversed.

This unexpected twist allowed researchers to measure how flexible people were in adjusting their choices. But it also revealed whether people impulsively changed their choice when the computer gave misleading feedback.

“Different players use different strategies, which depend on their genetic material. People’s tendency to change their choice immediately after receiving a punishment depends on which serotonin gene variant they inherited from their parents.

“The dopamine gene variant, on the other hand, exerts influence on whether people can stop themselves making the choice that was previously rewarded, but no longer is,” said den Ouden.

The findings reveal that both dopamine and serotonin are necessary for different forms of flexibility associated with receiving reward and punishment. Many neuropsychiatric disorders caused by abnormal dopamine and/or serotonin levels are associated with forms of inflexibility, such as addiction, anxiety, or Parkinson’s disease.

This research sheds light onto the notion that the choices we make are somewhat heritable. It also offers a better understanding of the relationship between brain chemicals and behavior in healthy people, which will ultimately help provide researchers with a better understanding of neuropsychiatric disorders.